In the conventional practice of color photography, silver halide film is developed by a chemical technique, requiring several steps consisting of latent image development, bleaching, and fixing. While this technique has been developed over many years and results in exceptional images, the technique requires several liquid chemical solutions and precise control of times and temperatures of development. Further, the conventional silver halide chemical development technique is not particularly suitable for utilization with compact developing apparatus. The chemical technique also is not easily performed in the home or small office.
Imaging systems that do not rely on conventional wet processing have received increased attention in recent years. Photothermographic imaging systems have been employed for producing silver images. Typically, these imaging systems have exhibited very low levels of radiation-sensitivity and have been utilized primarily where only low imaging speeds are required. The most common use of photothermographic elements is for copying documents and radiographic images. A method and apparatus for developing a heat developing film is disclosed in U.S. Pat. No. 5,587,767--Islam et al. Summaries of photothermographic imaging systems are published in Research Disclosure, Vol. 170, June 1978, Item 17029, and Vol. 299, March 1989, Item 29963. Thermally developed films have not been generally utilized in color photography. However, heat development color photographic materials have been disclosed, for example, in U.S. Pat. No. 4,021,240--Cerquone et al and U.S. Pat. No. 5,698,365--Taguchi et al, and commercial products such as Color Dry Silver supplied from Minnesota Mining and Manufacturing Co. and PICTROGRAPHY.RTM. and PICTROSTAT.RTM. supplied by Fuji Photo Film Co., Ltd. have been put on the market. Furthermore, U. K. Publication 2,318,645 discloses an imaging element capable of providing a retained viewable image when imagewise exposed and heated. It is proposed that such an element could comprise a color thermal film for photography that delivers satisfactory pictures.
A recent innovation in color negative film has made use of a thrust cartridge containing color negative film. Such cartridges are disclosed in U.S. Pat. No. 4,834,306--Robertson et al and U.S. Pat. No. 5,003,334--Pagano et al. The film contained in such a thrust cartridge may contain a magnetic layer that allows recording of information during manufacture, exposure, and development of the film. Such film is disclosed in U.S. Pat. No. 5,215,874--Sakakibara. The film and cartridge may contain additional provisions for data storage such as DX bar code data and frame number bar code data. Such elements are disclosed in U.S. Pat. No. 5,032,854--Smart et al, U.S. Pat. No. 5,229,585--Lemberger et al, and U.S. Pat. No. 4,965,628--Olliver et al. The thrust cartridge may also be made lighttight so that unexposed or imagewise exposed film that has been rewound into the cartridge may be stored without further exposure of the film within the cartridge. These thrust cartridge films have the advantage that they may be more easily manipulated for copying, digital reading, and storage.
The importance of information such as film type, film speed, film exposure information, and information relevant to the processing and subsequent use (e.g. printing or optical scanning) of the film is well understood. Virtually transparent magnetic layers or stripes on film provide a means to record such information. These magnetic layers or stripes provide for the recording of information during film manufacture, reading and/or recording of information during camera use, and reading and/or recording information during subsequent processing or optical scanning. There is a need to read and write magnetic data on thermographic film associated with the thermal processing. There is also a need to read and write magnetic data on thermographic film associated with the optical scanning. Reading and writing information on a magnetic coating or stripe on thermographic film requires solutions to problems different than those encountered in other apparatus. For example, the thermal development conditions may degrade and potentially erase the magnetic information stored on the film. There is therefore a need to read and store the magnetic information so that it may be rewritten onto the film after thermal processing.
The function of a film scanner is to measure optical density at many points on the film being scanned. The density of each pixel, or smallest region of the film being sensed, is measured by illuminating the region with light of a known light intensity and measuring the intensity of the light which is transmitted through the film. Color scans require measuring transmitted light intensity over known spectral bands. Such techniques are disclosed in U.S. Pat. No. 5,684,610--Brandestini et al. The transmitted light intensity may be measured electronically and the electronic record of the transmitted light may be digitized and stored as an electronic file representation of the film image.
The importance and utility of an electronic record of film images is widely known in the art. The electronic file may be easily duplicated and extensively manipulated. Color balance and tone scale may be adjusted. Sharpening and other algorithms to alter image structure may be applied. Annotations and/or graphical elements may be added to the film image data file. The scene may be easily cropped and digitally zoomed. An electronic record of a film image may be easily transmitted and communicated through existing electronic communication networks. The electronic record of a film image may also be output to a variety of output devices including ink jet and thermal wax digital printers. The electronic record may also be manipulated and stored in mass storage devices for rapid retrieval and subsequent processing. There is a need to optically scan thermographic film to provide an electronic file record of the film image information.
Optical writing of sensitometric tables and test patches onto conventional wet processed film to improve imaging system performance are known in the art. Such techniques are disclosed in U.S. Pat. No. 5,667,944--Reem et al. Optical writing of calibrated tablets and patches onto unexposed portions of film is of significant utility. Inspection of processed calibrated tablets or patches allows the processing conditions to be optimized for the remainder of the film strip. Furthermore, analysis of the calibrated tablets or patches allows printing and/or scanning algorithms to be refined to achieve an advantaged print or more useful electronic record of the film image data. For example, tone scale and color balance may be corrected and adjusted based on data obtained from calibrated tablets or patches. Optical writing provides a means to store other information on the film such as data associated with processing or scanning conditions. Optical writing also allows information to be written onto exposed regions of the film. For example, a time and date stamp that is readily apparent in a print may be written onto the film at the time of processing. Furthermore, by controlling the optical writing, graphical elements may be added to the original scene prior to processing. There is a need to provide for optical printing onto thermally developable film.